Controllable pitch propeller



Feb..24, 1953 J, NICHOLS 2,629,451

GON'EROLLABLE PITCH PROPELLER Filed Dec. 17. 1945 Feb. 24, 1953 H. J.NICHOLS 2,629,451

CONTROLLABLE PITCH PROPELLER Filed D90. 17. 1945 2 SHEETS-SHEET 2swam/com f/nee J Max/025 Patented Feb. 24, 1953 UNITED STATES PTENTOFFICE CONTROLLABLE PITCH PROPELLER Harry J. Nichols, New York, N. Y.

Application December 17, 1945, Serial No. 635,509

10 Claims. 1

This invention relates to controllable reversible pitch propellers, andparticularly to such propellers for marine use, and has for one of itsprincipal objects the provision of a propeller of the characterdescribed in which the pitch of the blades can be quickly and accuratelyregulated while the propeller is in rotation under load and in which theblades will be automatically locked against displacement from the pitchto which they have been set during such regulation.

I am aware that numerous variable pitch marine propellers have beenproposed and a few have actually been built and put into use. In eachinstance, however, insofar as I am aware, the variable pitch marinepropellers which have been proposed or put into use have beencharacterized by complexity, bulkiness, abnormal hub size, excessiveweight and cost, and other practical objections and disadvantages whichhave prevented their adoption for general use. I am further aware thatit has heretofore been proposed, by means of an electric motor and speedreducing gearing, to vary the pitch angle setting of the blades of amarine propeller. This latter type of pitch varying mechanismundoubtedly offers the possibility of largely overcoming the mainobjections and disadvantages recited above, and of meeting the need fora compact, reliable, and not too complicated and expensive variablepitch propeller. ceeded in devising compact gearing or other mechanismof sufficient torque augmenting power to enable a motor and associatedmechanism of practical size to be employed for such pitch changingpurposes. The present invention relates, therefore, to improvements inthis particular type of variable pitch marine propeller development.

One of the principal requirements of a controllable and reversiblepropeller of variable pitch type, in which a motor actuates the pitchchanging mechanism to vary and set the pitch, is that the actuatingmechanism between the motor shaft and the blade roots should greatlyaugment the motor torque (say between 2000 to 5000 times) without,however, introducing an excessive overall speed-reduction in themechanism. It has been found, by recent experiments that the torquewhich must be applied to the blade roots to vary the blade pitch whilethe propeller is operating at full speed and load (and particularly whenreversing the pitch under these conditions) is very exceeding in somecases cne half the propeller shaft torque. The application of torque ofthis relative magnitude to the blades obviously requires mechanism ofgreat strength and rigidity. Further, in order to reverse the bladepitch for emergency maneuvering, the mechanism must be relatively quickacting. Furthermore, in order to permit of automatic regulation of theblade pitch, as for example by However, the prior art has not suca speedgovernor, it is essential that the pitch actuating mechanism beself-looking in any position to which the pitch is set.

By my use of a novel compound planetary differential gear system, thedesired augmentation of the motor torque, quick reversing, andselflocking action are obtained in combination with compactness,simplicity, rigidity, reliability, high efiiciency, and reasonable cost.Such use lends itself to a construction in which the torque augmentingmechanism can be located completely within the hub itself, and the motorcan also be located within the hub in direct driving relation to thegearing.

The present invention thus contemplates an arrangement of pitchactuating mechanism in which the torque augmenting gearing as well asthe blade actuating gearing are wholly enclosed in the hub per se, andin which the pitch actuating motor can also be located in the hub,whereby the pitch of the blades can be quickly and positively variedwhile the propeller is rotating at full speed and power.

It is therefore a principal object of the invention to provide a novelcombination of gearing specially adapted to meet the requirements for apropeller of the class described and characterized by a uniquecombination of the qualities of compactness, simplicity, strength, hightorquegain, and self-locking action.

Another object is to provide a controllable pitch propeller system whichcan be readily applied to existing propulsive installations with theminimum of modification of existing components and arrangements, thussecuring substantial economies by modernizing marine installationsalready in service by the application of controllable pitch propellersthereto.

A further object is to provide an exceptionally simple, compact, andpowerful blade actuating mechanism which is economical to manufacture,easy to install and service, and which will ensure reliable operationfor long periods Without special attention or maintenance.

A further object is to provide a strong and rigid pitch varyingmechanism which eliminates any possibility of flutter or vibration ofthe blades in operation due to excessive elasticity or hack-lash in thepitch varying mechanism.

A further object is to provide a pitch varying system of unlimitedangular range, including full-feathering and reversing oi the blades,which is capable of changing the blade pitch in micrometric increments,yet also is capable of changing the pitch at a rapid rate formaneuvering and meeting emergencies.

A further object is to provide a pitch regulating system whose operatingspeed is independent of the speed of rotation of the propeller shaft.

A further object is to provide a blade pitchchanging motor and mechanismlocated entirely in the hub whereby the stresses due to the twistingmoment of the blades under load are confined to the hub, and at the sametime a rigid and powerful blade actuating mechanism of minimum size,inertia, and cost is obtained.

It has heretofore been proposed to mount a pitch changing motor for avariable pitch propeller in a shaft coupling, and also in the hub cap,but it is believed to be novel in the art to mount such a motor entirelywithin the hub as contemplated by the present invention, therebyobtaining various advantages as will become apparent as the descriptionproceeds.

With these and other objects in view, as well as other advantagesincident to the improved construction, the invention consists in thevarious parts and combinations thereof set forth and claimed, with theunderstanding that the several necessary elements constituting the samemay be varied in proportions and arrangement without departing from thenature and scope of the invention as defined in the appended claims.

To enable others skilled in the art to comp-rehend the severalunderlying features of this invention, that they may embody the same bysuitable modifications in structure and relation to meet the variouspractical applications contemplated by the invention, drawings showing apreferred embodiment of the invention form part of this disclosure, andin such drawings, like characters of reference denote correspondingparts in the several views in which:

Fig. 1 is a longitudinal half-sectional view of a propeller hubembodying the invention.

Fig. 2 is a transverse section taken on line 22 of Fig. 1.

Fig. 3 is a longitudinal half-sectional view of a drive shaft couplingembodying certain features of the invention.

Fig. 4 is an end view of the shaft coupling shown in Fig. 3.

Referring now to the drawings, and particularly to Figs. 3 and 4, apreferred construction of a controllable pitch propeller embodying theinvention is shown as comprising a main drive shaft I0, as for examplethe power output shaft of a propulsion prime mover, having a collar orannular flange I I upset or otherwise provided thereon at its outputend; and a tubular propeller shaft 30 having mounted thereon ademountable flange 3| fixed against rotary movement by means of a key 32and against longitudinal movement by a split locking ring 33 seated in agroove formed in propeller shaft 30 as shown. The two shafts are rigidlyconnected in driving relation by means of a novel unitary flangecoupling 20, the main structural component of which is a hollow cylinderor barrel 2|. Flange I I is preferably strongly fixed to barrel 2| by acircular series of socket-head cap screws I2, passing throughlongitudinal holes in that flange; while flange 3| is likewise fixed tobarrel 2| by similar sockethead cap screws 34 passing through flange 3|and ring 33, although conventional through bolts and nuts can of coursebe used to clamp the flanges and barrel tightly together in drivingrelation if such construction is preferred.

For purposes of electrical current supply to the pitch actuating motor Mand the electrical pitch transmitter T mounted in the propeller hub, ashereinafter described, there are suitably mounted on the exterior ofbarrel 2| but insulated therefrom by an insulating band 22 two series ofthree conducting slip rings designated by 23 and 24 respectively; andmounted to ride thereon are two groups of three brushes designated by I3and I4 respectively. Since the construction of brush holder assembliesis well known and not a part of this invention, the brushes I3 and I4are shown schematically and the brush holders therefor are omitted.Insulated metal bolts 25 fix slip rings 23 and 24 in position on barrel2| and also provide conducting paths from these rings to the oil-proof,insulated conductors 26 which are bound together in a sheath in wellknown manner to form an insulated cable 21. A conduit 35 is mountedcoaxially in the bore of propeller shaft 3|] by means of perforatedspacers 3'! (one of which is shown while others are suitably locatedalong the length of the bore) for carrying cable 21 to the hub 40. (SeeFig. 1.) A sealing cap 36 is screwed on the end of conduit 35 and servesto seal the point of entry of cable 2! against the entrance of oil intothe conduit.

The unitary flange coupling 20 is also provided with rotary shaftsealing means I5 to enable lubricating oil to be supplied to themechanism housed in the hub. Lubricating oil is supplied to the sealingmeans from a tank located above the water line by suitable piping inwell known manner and therefore not shown. The 1ubricat ing oil fillsall the void spaces in the coupling, propeller shaft, hub and pitchactuating motor M for the three-fold purpose of providing continuous oillubrication to all the bearings and working points, conducting heat awayfrom the motor windings, and maintaining a certain hydrostatic pressurein the hub to ensure that water will not enter the hub in event ofseepage or leakage at the hub joints or packings. The rotary shaftsealing means comprises a ring housing I6, preferably split into twohalves, provided with two shaft packing rings I6, of say felt; and aninternal hollow sealing ring I! fit closely but rotatably to theperiphery of drum 2| and having annular labyrinth grooves disposedaround the internal surfaces which bear on the periphery of the drum toimpede the leakage of oil therebetween. The upper half IBa of the splithousing I6 is provided with a threaded nipple l8 adapted for assemblywith a suitable pipe fitting of commercial type. A nozzle I9 is tightlyfit in the bore of nipple I8 and extends through a closely fit hole inthe shell portion of sealing ring 11, thereby to provide a port of entryfor oil into the sealed space within ring I'I. Suitably placed radialholes 2 la drilled in barrel 2| provide passage for the oil from thesealing ring into the interior of coupling 20. The lower half IBb of thesplit housing is provided with a second threaded nipple I8, similar toentrance nipple I8, but the nozzle I9 and the hole in the inner sealingring are omitted, whereby nipple I8 serves as an exit port or drain forany oil which may leak from the inner sealing ring I! into the housingI6. It is assumed that suitable piping is provided from nipple It to anoil sump, from which the oil drained from the housing is returned touse. Since there is no oil pressure within the housing, it will beevident that the role of soft packings I6 is merely to prevent seepageof oil along the surface of drum 2|, the inner sealing ring I!constituting the effective oil seal with respect to the coupling barrel.Housing I6 is mounted by screws II! on stationary supporting means (notshown). It will be apparant to those skilled in the art that the novelrotary oil sealing means described is characterised by structuralsimplicity, ease of manufacture and assembly, and long wearingqualities.

Referring now to Figs. 1 and 2, which show one form of propeller hubconstruction according to the invention, such includes a main hub membertil, herein for brevity termed a hub, and a hub cap ll which closes theoutboard end of the hub, said hub being rigidly affixed to flange 38,upset or otherwise provided on the outboard end of pro peller shaft 38,by a series of circularly arranged bolts 39 (one being shown) orotherwise as desired. The hub cap 4! is secured to hub 40 by a pluralityof longitudinally disposed cap screws 42 as shown, or otherwise asdesired. Hub 40 has a plurality of radially extending circular openingsor blade sockets 43 (four in the case illustrated) each adapted to mountrotatably a blade 45 by means presently to be described. Each bladesocket is step bored to receive a closely fitted locking ring 46 adaptedto be secured therein by multiple cap screws ll as shown. A fiat, thincover ring d8 is placed in the blade socket to cover the heads of capscrews 1' and a sealing ring 49, having a slightly arched section toprovide a limited amount of resiliency when subjected to pressure, isplaced in the socket over the cover ring to abut against the bossportion 5i of blade 55, which latter is also provided with an axial stubshaft 52. Secured to each blade by a plurality of cap screws 53 seatedin counter-bored holes through the boss 5| is a gear ring 54 having abevel gear 55 formed thereon and mounted in the inner bore of the bladesocket for inter- E.

meshing engagement with a master bevel gear 56 mounted axially androtatably in an axial bore of hub 45. A second ring bevel or unison gear5'8 may be rotatably mounted on an internal boss so, formed from theback wall of hub 58, for Z meshing engagement with the blade bevel gears55, whereby the rotation of the blades in unison is assisted in event ofbinding of the blade mountings, although this unison gear is notessential under normal operating conditions. In case the unison gear 57is used, a ring thrust washer 58 is preferably provided between the backof the unison gear and the hub wall, as shown, to reduce friction and toprovide an adjustable and renewable thrust bearing surface at thatpoint.

The blades to are assembled in the blade sockets d3 of the hub in thefollowing manner: The thrust washer 58 is first assembled in theposition shown over the boss to of hub 58, and

then unison gear 5'! is assembled on boss 58 in the position shown. Ablade gear-ring 55 is then dropped. into position in predeterminedangular relation, with the bevel teeth 55 thereof in mesh with the teethof the unison gear El. The looking ring at is next placed in the socketand the cap screws c1 screwed tightly into place, followed by cover ring58 and sealing ring :9. The stub shaft 52 of blade is then entered intothe bore of gear ring 5 5 and the blade turned until the counter-boredbolt holes in the blade boss 5! align with the proper tapped holes inthe ring 5%, whereupon the cap screws 53 are entered in these alignedholes and screwed tightly in place. The sockets in the heads of the capscrews are then preferably filled with a non-corrodable fusible alloy,as for example plumbers solder, by the customary tinning and castingprocess; the bolt holes also being entirely filled and then filedsmoothly to the contour of the boss, thereb to prevent loosening of thecap screw, to seal the bolt holes, and to provide a smooth externalsurface for the blade boss.

The unison gear 57 and the master bevel gear 53 are preferably providedwith a number of teeth divisible by th number of blades, and the bladebevel gears 55 with an even number of teeth, whereby all the blades,gears, rings, bolt holes, and other components and details can beconstructed in identical manner for interchangeable assembly. Theconstruction described provides the practical advantages of fullyinterchangeable blades and blade mountings, and also facilitatesaccurate coordination of the pitches of the individual blades. In theevent one or more blades are damaged in service, a new blade can befitted merely by removing the cap screws and the damaged blade, placingthe new blade in position, replacing and tightening the cap screws, andrescaling the bolt holes as before. The rest of the hub mechanism neednot be disturbed during such blade replacement. It will be appreciatedby those skilled in the art that the facility with which blades can beassembled and replaced provides many practical advantages inmanufacture, assembly, maintenance and repairs, resulting from theconstruction shown.

A pitch changing motor M is mounted within the hub so in the spacebounded by the bevel gearing B5, 56 and with its axis and driving shaft68 coaxial with the axis of the hub and the proeller shaft, therebyobtaining symmetry of the masses in the hub and preserving dynamicbalance of the hub and its mechanism.

The pitch changing motor M is preferably a polyphase induction motorhaving a squirrel-cage rotor, in which case the motor frame can be ofopen type to enable the lubricating oil to circulate inside the motorfor cooling and lubricating purposes. However, a totally enclosed motorof any type can be used, but less advantageously because of reducedheat-radiating ability. Since the motor itself can be any one of variouswellknown commercial types, showing the description 1 details thereof isdeemed unnecessary.

Firmly secured to the end frame of motor M nearest the propeller shaft'30, or integral with the frame thereof if preferred, is a cylindricalhousing 62 adapted to house in a sealed space "therein an electricaltransmitter T comprising part of an electrical pitch indicating system,which system however is not a part of the present invention. Anelectrical pitch controlling and pitch indicating system suitable foruse with the present invention and with the motor submerged in the hubis fully shown and described in my copending application Serial No.618,643, filed September 26, 1945. For present purposes, it is to beunderstood that motor M is provided with an extension shaft adapted toactuate the electrical transmitter T sealed in housing 62, and thatelectrical connections to that transmitter and to motor M are providedby the cable 27 in conduit 35 which terminates in housing 62 in themanner shown. Housing 62 also serves as a fixed mounting means for motorM in hub 40 as shown, relative rotation thereof being prevented by a keyEl as shown.

The power output shaft 58 of motor M provides actuating torque for atorque-increasing coinpound differential gear mechanism comprising amain feature of the invention and now to be described with particularreference to Figs. 1 and 2. Power output shaft 60 is rotatably mountedin a bearing 63 supported in a spider B4 of cap 4| and has tightly fixedthereon a driving sun pinion S. A planetary carrier A, comprising twodiscs 66, '65 held firmly in spaced parallel position by pillars 67 (seeFig. 2), carries a plurality of compound planet pinions PI and P2rotatably mounted on axles supported by the discs. Three pairs ofcompound pinions are shown in Fig. 2, but two or more pairs may be used,depending upon load conditions. Each pair of pinions Pl, P2 arepreferably made integral, but if not, they must be tightly assembledagainst relative rotation on an axle or quill shaft. Pinion Pi is inmeshing engagement with a stationary internal gear GI fixed to hub 40 bycap screws 88; while pinion P2 is in meshing engagement with rotatabledriven internal gear G2 integral with master bevel gear 56. A thrustwasher 63 is mounted between gears GI and G2 to take the axial reactionthrust of bevel gear 56.

To secure smooth running of the gear trains and self-locking action, itis preferred that the circular pitches of the gears in train S, PI, GI,and train P2, G2 respectively, be approximately in the ratio G2P'2/GIP|.

The planetary compound differential gear train of the invention ischaracterized by its compactness and simplicity, by the large torquegain readily obtainable thereby, and by the unusual combination of highefiiciency and self-locking action. The following example willillustrate the computation of a typical gear ratio:

Let the sun pinion S have 16 teeth, the meshing planet pinion PI have 17teeth, the compound planet pinion P2 have 16 teeth, the stationaryinternal gear, hereafter termed orbit gear GI, have 50 teeth, and thedriven intern-a1 gear, hereafter termed orbit gear G2, have 47 teeth.For one turn of sun pinion S, which acts as the primary driver elementof the entire gear train, the rotation of the planetary carrier A willbe:

S 16 E S+G1-l6+50 66' Considering next the planetary carrier A as thedriving member of the gear train, one turn of the planetary carrierwill, due to the differential action of compound planet pinions PI andP2 meshing with gears GI and G2 respectively, produce a rotation ofdriven gear G2 of:

.2424 turn But since for one turn of the sun pinion S the planetarycarrier makes of 'a turn, the relative rotation of G2 will be:

It is known that the mechanical efficiency of a pair of meshing gears ofproper material, form, construction and lubrication is approximately98%, and since there are three pairs of meshing gears in the gear train,the efficiency E would be equal to .98 =.94. Therefore, the

Torque factor=3296 .94=3100X approx. Assuming next that the rated motorspeed were 3240 R. P. M., the motor shaft torque per motor horse-powerwould be equal to:

X 1=19.4 lbs. inches/H. P.

turn

and the torque delivered by the gear train would be:

3100 19.4=60,500 lbs. inches/H. P. approx.

Assuming further that a pitch change of 60 represents a fullpitch-reversal from ahead to astern, the reversing time from full-aheadto full-astern would be:

gi 2g -=l0.2 seconds approx.

In like manner, various combinations of pinions and gears may beselected, by following the teaching of the invention, to suit a widevariety of desired torque factors and rates of pitch change.

The sample calculations given above are illustrative of thetorque-increasing power and substantial advantages of the highefiiciency, high torque, compact gearing of the present invention.Obviously, with such large torque/H. P. ratios available, anexceptionally small and high-speed motor M can be used to advantage andyet the pitch can be changed at a rapid rate thereby when the propelleris in rotation under full load. It is thus evident that the efiicienttorque increasing gearing of the invention makes it possible andpracticable to locate the pitch changing motor entirely within theconstricted confines of the hub, thereby securing the benefits ofmaximum structural rigidity, with minimum size, inertia, and cost of thepitch changing mechanism.

An additional important advantage arises from the self-locking action ofthe planetary compound differential gear train of the present invention.It is well established that the reaction of the propeller blades due tocentrifugal force and fluid reaction forces produce a very powerfultwisting moment tending to turn the blades axially when the propeller isin rotation under full load. This twisting moment is transmitted by theblade gears 55 to master gear 56, and therefore tends to rotate drivengear G2 relative to stationary gear Gi. With the gear train of thepresent invention, the gears G5 and G2 are out nearly to the same pitchcircle, as are likewise pinion PI and P2, despite the different numberof teeth in these pairs. Hence the effect of this twisting moment actingto turn G2 relative to GI is to produce opposing tangential shear forceson the pinion teeth; but since these pinions are either made integral orare non-rotatably assembled on a common axle, the shear force describedcauses the pinions to act like keys between the two gears, locking thesegears together rigidly against any counter-torque less than the shearvalue of the gear teeth. Due to the selflocking action described, theblade twisting torque is absorbed by the teeth of gears GI, G2, andpinions Pi, P2, hence there is no tendency for sun pinion S, nor themotor shaft 60, to be rotated by the blade reaction. Consequently, theblade pitch is maintained by the difierential gearing as set by thepitch actuating mechanism. Otherwise, complicated braking means, or theequivalent, would have to be applied to the motor shaft or gear trainmembers to prevent counterrotation by the blade reaction and creep ofthe blade pitch from the set position. This would greatly complicate, ifnot render entirely impractical, any construotion for mounting the pitchchanging motor in the hub. It thus becomes apparent that theself-locking characteristic of the compound differential gearing of 9the invention, as well as the high torque efiiciency thereof, is a vitalfactor in providing the characteristic simplicity and practicality ofthe construction of the invention.

The operation of the pitch changing mechanism of the invention is asfollows: Pitch controlling means not shown, as for example that shownand described in my copendin'g application Serial No. 618,643, filedSeptember 26, 1945, applies electrical current to the brushes l3 whichcurrent is conducted by slip rings 23, via conductors 26 of cable 21, tomotor M to energize same in one direction or the other. Motor shaft Bilrotates accordingly to drive sun pinion S, which in turn drives pinionPl in mesh with stationar internal gear GI to produce rotation ofplanetary carrier A. As planetary carrier A revolves, pinions PI and P2planetate in gears GI and G2 respectively, producing creeping differential rotation of gear G2 relative to gear GI due to the difierentialgear action previously described. Gear GZ rotates master bevel gear 55integral therewith, which latter in turn rotates the blade bevel gears55 to vary the pitch of the blades in unison. When the motor current iscut-off, the motor shaft quickly stops and due to the self-lockingaction of the diiferential gearing as previously described, the bladepitch remains in the set position until subsequent pitchchanging asdescribed.

It is to be noted that the blades are rigidly positioned by the blademountings and the teeth of the bevel gears, internal gears, and pinions.All the gear teeth in the gear train can be cut with a minimum ofback-lash, and since there are no elastic members in the primary bladeactuating mechanism, flutter r vibration of the blades due to excessiveback-lash or elastic strain is effectually suppressed. Further, sincethe blade reaction stresses are confined to the hub, there is nopossibility of critical vibration effects due to elastic shaftreactions, etc. thereby avoiding troublesome vibratory effects whichhave heretofore been experienced in applications of the prior art.

Concurrently with the pitch changing action described above, the motor Mdrives the electrical transmitter T, which latter produces electricalindications of the direction and degree of the blade pitch change. These-electrical indica tions are transinitted by the conductors of cable 21and the associated slip-rings and brushes to remote receiving apparatus,as for example that shown in my copending application Serial No.618,643, filed September 26, 1945, where the indications are utilizedfor pitch indicating and automatic follow-up control purposes.

It is to be noted that the pitch changing system of the inventionenables the blade pitch to be set to any angular position, since thereis no mechanical limitation on the axial rotation of the blades.Consequently, the blade pitch can be set, by suitable motor controlmeans, to neutral pitch, to all forward and reverse operating pitches,and to full feathered pitch in the ahead or reverse semi-circles. Pitchrange limitation, or so-called pitch-block, can be set by appropriatemeans forming part of the pitch control apparatus; but if the limits soset areexceeded, there is no possibility of jambing, deranging, ordamaging the pitch changing mechanism. Thus the important objective ofunlimited pitch range is secured, so far as the pitch changing mechanismof the invention is concerned, there- 10 by making this mechanismsuitable for universal application.

It is of course obvious that the rate of pitch change is entirelyindependent of the propeller shaft speed, and therefore pitch change canbe accomplished with equal facility and speed whether the propellershaft be at rest or in rotation at full speed. It is also apparent thatby providing a gear system of high efficiency, by providing a pitchchanging motor and mechanism of low inertia, by eliminating externalmechanical connections, by confining the operating forces to thepropeller hub, and by inherent simplicity, economy, reliability, andcompactness, the controllable pitch propeller system of the inventionovercomes the main disadvantages which have heretofore limited thepractical application of electro-mechanical variable pitch propellers ofthe prior art.

Without further description, it is believed evident that the mechanismof the invention provides a powerful, eilicient and practical means forvarying the blade pitch under all operating conditions. It is also to beparticularly noted that the construction of controllable reversiblepitch propellers provided by the invention is readily adaptable to themodernization of vessels having fixed blade propellers without extensivealteration of conventional propulsion arrangements.

I claim:

1. A variable pitch marine propeller organizati'on comprising, incombination, a propeller hub structure including a main hub memberhaving an axial bore and a radial socket for each 1 blade; blades eachhaving a spindle rotatably secured in bearings in a blade socket; abevel blade gear fixed to each blade spindle; a bevel master gearjournaled rotatably in said axial bore and meshing in driving relationwith said blade gears; a reversible motor mounted in the bore of saidh'ub member and generally Within the space bounded by said bevel bladegears; and a differential planetary gear train mounted substantiallywithin said hub member outwardly of said motor and comprising a sunpinion driven by said motor, an internal ring gear fast to said hubmember, a driven internal gear fixed to said master bevel gear, andplanetary pinions carried by a rotary carrier mounted axially in saidhub and driven by said sun pinion and meshing with said internal gears,said gear train being adapted and connected to receive driving torquefrom said motor and to deliver greatly increased driving torque to saidmaster gear, thereby to vary the pitch of the blades.

2. A variable pitch marine propeller organ- 'i'zation combining apropeller hub member adapted for mounting on the end of a shaft andhaving an axial bore and radial blade sockets; blades each having a rootportion journaled for pitch changing movement in a socket; a bevel bladegear fixed on the inner end of each of said root portions; a bevelmaster gear journaled coaxially within said axial bore and meshing indriving relation with said blade gears; a torque increasing differentialplanetary gear train mounted substantially within said hub member andhaving a driving connection to said master gear; and a reversibleelectric motor mounted in the bore of said hub member and substantiallywithin the space bounded by said bevel blade and said bevel master gearsand having a driving connection to said planetary gear train foreffecting blade pitch change.

3. A variable pitch marine propeller organization combining a propellerhub structure including a main hub member for mounting on a shaft andhaving an axial bore; blades each having a part secured in bearings insaid hub member for pitch change; a bevel blade gear fixed to the innerend of each said part; a bevel master gear journaled rotatably in saidhub member and meshing in driving relation with said blade gears; areversible motor mounted in the bore of said hub member and generallywithin the length of the bore bounded by said blade bevel gears; and aspeed reducing differential planetary gear train mounted substantiallywithin said hub member and having a driven connection to said motor anda driving connection to said master gear, whereby the pitch of theblades can be changed upon operation of said motor.

4. In a variable pitch propeller organization, in combination: a hollowpropeller shaft; a propeller including a main hub member rigidly affixedto the outboard end of said shaft and a hub cap rigidly affixed to theoutboard end of said hub member; blades mounted for axial rotation insaid hub member for pitch change; bevel gearing for turning said bladesaxially mounted entirely within said hub; a reversible motor fixedWithin said hub member centrally with respect to said bevel gearing; anda high ratio difierential planetary gearing mounted substantially withinsaid hub member and having a driven connection to said motor and adriving connection to said bevel gearing, thereby to turn said bladesaxially in unison to change their pitch.

5. A variable pitch propeller system having, in combination, a hollowpropeller shaft; a hub structure including a main hub member affixed tothe outboard end of said shaft and a hub cap affixed to the outboard endof said hub member; blades mounted for axial rotation in said hubmember; bevel gearing for rotating said blades mounted in said hubmember; speed reducing differential planetary gearing mountedsubstantially within said hub member and having a driving connection tosaid bevel gearing; a reversible electric motor fixed centrally in saidhub member and axially inwardly of said planetary gearing and having adriving connection thereto; coupling means for connecting said propellershaft to a drive shaft; electrical circuits for conducting electriccurrent to said motor to operate it in either direction extending fromsaid motor and through said hollow shaft to said coupling means; andcurrent conducting means carried externally by said coupling means forconnecting an external source of current to said electrical circuits.

6. A variable pitch propeller comprising, in combination, a hubstructure including a hollow main hub member for mounting on theoutboard end of a drive shaft and a hub cap closing the outboard end ofsaid hub member; radial blades each having a part secured in said hubmember for axial rotation; a bevel gear fixed on each said part; amaster bevel gear mounted coaxially and rotatably in said hub member andmeshing in driving relation with the first-named bevel gears; areversible motor fixed centrally and coaxially within said hub member;and differential planetary gearing mounted in said hub structure axiallyoutward of said motor and operatively arranged and connected for greatlyincreasing the driving torque produced by said mo- ,tor and transmittingsame to said master bevel gear, thereby to turn said blades axially inunison to vary their pitch.

7. A controllable reversible pitch marine propeller combining a hollowhub member for mounting on a propeller shaft; a hub cap fastened tightlyto the outboard end of said hub member; blades swiveled for axialrotation in said hub member; bevel gearing for rotating said bladesaxially enclosed entirely within said hub member; a motor fixedcentrally within said hub member; and torque increasing differentialplanetary gearing mounted partly in said hub member and partly in saidhub cap, said planetary gearing having a driven connection to said motorand a driving connection to said bevel gearing.

8. In a controllable reversible pitch propeller including a hollow hubstructure including a main hub member mounting axially rotatable bladesand a hub cap closin the outboard end of said hub member; powermechanism for rotating said blades and being substantially completelyenclosed within said hub member, said mechanism comprising bevel gearingfor angularly displacing said blades in unison mounted entirely withinsaid hub member, a reversible motor fixed centrally within said hubmember, and speed reducing differential planetary gearing operativelyconnected to be driven by said motor and to drive said bevel gearingmounted in said hub member axially outward of said motor.

9. A variable pitch propeller combining a hollow hub structure includinga main hub member and a hub cap closing the outboard end of said hubmember; blades mounted for axial rotation in said hub member; bevelgearing for displacing said blades angularly mounted entirely withinsaid hub member; a reversible motor fixed centrally in said hub member;and a differential planetary gearin characterized by a high torqueincreasing ratio and self-locking action mounted in said hub structureaxially outward of said motor, said gearing being operatively arrangedand connected for transmitting and multiplying torque from said motor tosaid bevel gearing whereby the pitch of the blades may be set byoperation of said motor and the self-locking action of said differentialgearing will maintain the blades at the pitch so set.

10. A variable pitch propeller including a main hub member and a hub capafiixed to the outboard end of said hub member; blades pivoted forrotation in said hub member; bevel gearing for rotating said bladescompletely enclosed within said hub member; a reversible electric motorfixed substantially centrally within said hub member; and speed reducingdifferential planetary gearing mounted substantially within said hubmember and having a driven connection with said motor and a drivingconnection with said bevel gearing, whereby the propeller blades may berotated upon operation of the electric motor.

HARRY J. NICHOLS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,828,303 Turnbull Oct. 20, 19311,951,320 Blanchard Mar. 13, 1934 1,967,302 Gannett July 24, 19342,124,078 Palmer et al July 19, 1938 2,245,251 Chilton June 10, 19412,327,217 Reiber et al Aug. 17, 1943 2,392,364 Caldwell et al. Jan. 8,1946 2,397,357 Kundig Mar. 26, 1946 2,425,353 SpitZer Aug. 12, 1947

